Forebrain PreQuiz

Question 1

What are the three multimodal association areas of the neocortex?

Answer 1

Frontal multimodal cortex: 9-11, 45-47

Temporal multimodal cortex: 21, 38

Parietal multimodal cortex: 7, 39

Question 2

What are the major functions of the parietal multimodal cortex?

Answer 2

Parietal multimodal cortex: 7,39- sits at the intersection of the somatosensory and visual cortex

• Agency: the feeling that one is in charge of making decisions
• Attention
• Spatial localization
• Sense of body localization in space
• ->Involved in complex associations, attentive behaviors, and sense of self

–> i.e. visually guided reaching

Question 3

What are the two functionally distinct regions of the cortex?

Answer 3

These two divisions of the cortex have different objectives, yet are mutually dependent on each other.

1. The frontal (“executive”) cortex- generating actions that act on the world

–> Convergent system to generate muscle contraction

–> Feedforward and feedback between primary motor cortex, premotor cortex, and supplementary motor cortex

2. The caudal (“perceptual”) cortex- perceiving the world

–>From sensory cortex: Auditory and visual output→divergent input to association cortex to allow for complex understanding

Question 4

Describe the possible conditions resulting from lesions in the parietal cortex.

Answer 4

CONTRALATERAL NEGLECT
-neglect: the inability to perceive objects in the environment

–>Damage to the non-dominant (i.e. right) parietal cortex can lead to an inability to perceive objects in the contralateral (“left in this example”) side of the world

ATTENTION DEFICIT: can impair attention

TACTILE AGNOSIA aka astereoagnosia: the inability to identify objects by touch despite normal sensory ability
–> requires interaction of somatosensory (touch) and visual information (3D “visualization” of the objects based on touch)

–> integration generally occurs in the parietal multimodal cortex

OPTIC APRAXIA: dimage to the parietal cortex can cause deficits in visual scanning of the environment

OPTIC ATAXIA: damage to the parietal cortex can cause deficits in hand-eye coordination

BALINT’S SYNDROME: Results from bilateral damage to parietal associational cortex

• simultanagnosia: the inability to perceive more than one object at a time
• optic apraxia: difficulty in scanning through the visual field
• optic ataxia: trouble with visually guided reaching

Question 5

Describe extinction of the contralateral input in contralateral neglect.

Answer 5

Parietal cortex

-very subtle sensory impairments that only manifest when symmetrical stimuli occur simultaneously on both sides of the body → extinction of the contralateral input

–>Swenson video: when patient received input bilaterally, he could only register the right side

–>Mild example of extinct of response to left visual field

Question 6

What are the major functions of the temporal multimodal cortex?

Answer 6

The temporal associational areas, including Brodmann areas 21 and 22

–process auditory and visual information

• important in object recognition, including recognition of faces
• -> temporal – spend time with ones you love (recognition of faces)

–>tends to be lateralized to the right temporal cortex

–>important for object recognition and language comprehension